The larva feeds on oak species such as Quercus robur, Quercus pubescens or Q. petraea. In the south (e.g. Greece), I also observed larvae on Quercus coccifera and Quercus frainetto. Finally, I tapped them from Quercus ilex in Sardinia. The larva usually lives on older, blooming trees and contrary to Satyrium ilicis hardly on younger, small bushes.
Quercusia quercus inhabits oak forests of all kinds, grasslands with individual oaks etc. Quercusia quercus is found even in urban areas if some older oaks are present.
The caterpillar overwinters in the egg shell. The eggs are often found on the base of buds on the tip of the twig. Quercusia quercus is usually ovipositing on tall oaks and only rarely also on higher growing oak scrub. The caterpillar is fully-grown in May or early June, and the butterflies fly from late June to August.
Endangerment: regionally endangered or decreasing
Quercusia quercus is locally in slight decline due to conversion of oak-rich forests into spruce, maple or beech monocultures. Nevertheless, it is in many regions one of the most common butterfly species, if appropriate detection methods are used (searchinf for eggs, tapping larvae with a stick).
The adults are most likely to be observed near the ground in the morning. At other times they live more high up in the trees.
Quercusia quercus occurs throughout most of Europe (except the oak-free northern and Central Scandinavia), North Africa and wide parts of temperate Asia to Kazakhstan.